reading

README.md

@@ -138,6 +138,12 @@ The interrupt 0 exits the program. The exit code is passed in `r0`.
 
 ### `int 1`
 
-The interrupt 0 writes a string to standard output. `r0` contains the address of the string data.
+The interrupt 1 writes a string to standard output. `r0` contains the address of the string data.
 `r1` contains the length of the string. The string is forwarded as raw bytes to the OS.
-After the interrupt completed, `r0` will contain a 0 if writing was successful, or a `1` if it failed.
+After the interrupt completed, `r0` will contain a `0` if writing was successful, or a `1` if it failed.
+
+### `int 2`
+
+The interrupt 2 reads in a UTF-8 string from stdin. `r0` contains the address of the buffer for the data.
+`r1` contains the length of the buffer. The interrupt returns after the buffer has been filled. If reading fails,
+`1` will be put into `r0`, if it was successful, `0`.

doc/src/02_architecture_constraints.adoc

@@ -5,7 +5,7 @@
 |===
 |Constraint|Reason
 |Interpreter|Because the time for implementation is limited, the simpler option of an interpreter has to be chosen over a compiler.
-|4 weeks limited time|The time of the assignment
+|4 weeks limited time|The time of the assignment.
 |===
 
 == Conventions

src/interpret.rs

@@ -9,7 +9,7 @@
 //! Decimal 1
 //! ```
 
-use std::io::Write;
+use std::io::{Read, Write};
 
 use logos::Span;
 
@@ -113,6 +113,13 @@ impl InterpretCtx {
                 let is_ok = std::io::stdout().lock().write_all(slice).is_ok();
                 *self.reg_mut(Register(0)) = if is_ok { 0 } else { 1 };
             }
+            2 => {
+                let buffer_addr = self.reg_addr(Register(0));
+                let buffer_len = self.reg_addr(Register(1));
+                let slice = &mut self.memory[buffer_addr..][..buffer_len];
+                let is_ok = std::io::stdin().read_exact(slice).is_ok();
+                *self.reg_mut(Register(0)) = if is_ok { 0 } else { 1 };
+            }
             _ => panic!("invalid interrupt!"),
         }
     }